A torn-off cover of Fortune Magazine is pasted to the wall outside the cafe in building number 40 of the Google campus in Silicon Valley. The issue from December 2004 poses the question: Google - Is this company worth $165 a share? The headline must bring a wry smile to workers as they line up for their free lunch, prepared until recently by the Grateful Dead's former chef.

The shares, which floated on Wall Street at $85 last August, have since climbed further still to $239. The flotation has made a lot of people in Google very rich. Founders Larry Page and Sergey Brin, both 31, are worth about $9bn apiece. "I don't know if it has changed the culture but it has allowed a lot of people to buy houses," said chief executive Eric Schmidt.